资源环境科技发展态势分析平台

We report the first statistical survey of the oxygen ion cyclotron harmonic waves observed by Van Allen Probes throughout the mission. Our statistical study shows that the waves occurred over and across all magnetic local time. More than 50% of the events were observed just outside the plasmapause, and the typical wave amplitude is between and several nT. The frequency spacing between two consecutive wave harmonics decreases with increasing L but stabilizes when . The frequency spacing is larger than the local oxygen ion gyrofrequency for many events, especially those observed at larger L, suggesting that these waves propagated there from lower L shell regions. The waves are mainly on the dayside at under quiet geomagnetic conditions, but can occur at lower L shells with a more uniform MLT distribution under more active geomagnetic conditions.